Method of treating water resistant paper



Cd. 2 1946- w. H. MCDOWELL METHOD OF TREATING WATER RESISTANT PAPERFiledIMay 15 1945 WENDELL H. MCDOWELL INVENTOR lawzi A RNEYS Itherefrom.

Patented Oct. 22, 1946 time or TREATING WATER RESISTANT PAPER Wendell n.McDowell, Rochester, N. Y., assignor to Eastman Kodak Company,Rochester, N. Y.,

a corporation of New Jersey Application May 15,1945, Serial No. 593,829-

This invention relates to a method of treating meltI -.:coated,-waterresistant paper in which the-melt coating of the paper is treated withonly I enough of a lower monohydroxy alcohol towet the surface ,ofthecoating and is thenevaporated Recently the coating of paper with hotfluid 6 Claims. (01.117-62) which decrease the advantages in the use ofsuch a procedure. In other cases where thermoplastic sheeting hasexhibited sticking, thin layers of melts 'consistln'gof a celluloseester and a plasticizer has become-of interest, particularly for. thepreparation of water resistant paper suitable for photographic purposes.This melt coated paper is described in U. S. application, Serial No.553,804 of Hollis T. Galley, filed September 12,

cellulose esters from solution of the esters in volatile solvents havebeen applied thereto. the present situation this merely adds to theweight of the photographic paper and also presents'other difficulties,such as the effect of the volatile'solvents on the melt coating whichhas already been applied. Therefore, none of the methods which haspreviously been considered for cellulose ester sheeting have beenregarded with too much favor for inhibiting the adhesive- 1944, "and in."UQSI applications, Serial Nos. f

512,051 and-512,052 of salo' and. Vivian, filed Novemberwz7; 19i'3"whichhave matured into PatentsNos'i25387fl73 and 2,387,774. In the use.

of photographic paper for picture making it is ness of melt coatings.

One object of my invention is to provide a method of treating meltcoated paper so as to often desjirable 'arter'a photographic print has,

been developed, fixed, and washed to pass it over hot meta'l' 'dryingsurfaces such as heatedjtoa,

temperatureof 200-'-260 F. whrebyI'the photo+ graphic" paper is quicklydried, thus k say and contributing to the quality of the pro obtained.As long as-the hot surfaces are 'mainpaper'by this means is verysatisfactory.

In those cases, however, where melt 'coated paper has been employed asthe s'upportrfor a photographic emulsion, it has been found that'prevent sticking of that paper to hot metal drying surfaces. Anotherobject of my invention is to provide a method of treating melt coatedpaper .to inhibit sticking of that material to hot surfaces,

. which method does not increase the weight or taine'dbelow the meltingtemperature of the coat-' ping, drying of the} ordinary-typ photographicsticking of the paper to the hot metal surface may .occur in the dryingoperation. The melt coated water resistant paper ordinarily contains acoating of cellulose acetate'buty-rate plasticized with ,a stable,high-boiling material such, for

instancejas a mixture of dibutyl' sebacate and butylstearate or of di-2-ethyl he iyl-phthalate and butyl stearate. Becauseof'th'e natureof thiscoated material, methods of drying the'fp'hotoalter the surfacecharacteristics of the melt coating. A further object of my invention istoprovide a simple, easily operated method of treating melt coated paperto decrease its sticking properties.

dampenedjor slightly wetted with a lower aliphatic alcohol, whichalcohol is then evaporated therefrom provides a surface which will notstick to hot metal'drying surfaces such as are ordinarily employed indrying photographic prints or in ferrotyping operations. In its broadestaspects my invention comprises the treatment of paper which has beenmelt coated on at least one surface with a small amount of alcohol, onthat surface,

j iwhich is preferablyapplied only inl an amount,

, j f-insufiicientto run off the same. The melt coated graphlr? paperless convenient "than the use of hot surfaces have beennecessaryg-Heretofore where thermoplastic sheeting has exhibited stickingproperties, such as upoi'r bind ing that material together forshipping-or storage, it has been suggested that ,if'the surface of thesheeting was roughened or microscopically pitted, sticking would notoccur. Although methods of this nature might be useful for some typesofthermoplastic sheeting, the presence of paper thesurface of the meltcoating of which is thus dampenedwith the alcohol is preferably almostimmediately treated to drive off the alcohol such as by passage of theso-dampened paper through a heated chamber. The surface so treated willnot become tacky' upon contacting with a hot metal drying surface suchas having a temperature of 200-260 F. and no adhesion to the metal takesplace. In the process inaccorda roughened surface on photographic paperis not particularly desirable.

Other methods such as heating the paper in a hot chamber and then icooling, prior to packing have been considered. However, in practice,difliculties are met with ance with my invention only enough alcohol isemployed to wet the surface and, therefore, there is no substantialwashing out of any of the materials which are present such as wouldoccur by an immersion operation.

One procedure whichmight suggestitself as 3 being remedial of thesticking characteristics of melt coated paper would be to employ a meltcoat- I have found that melt coated paper which is cellulose position.

paper was treated) V sion had first-been applied to :the paperv before,or

ing composition in which tne amount of plasticizer employed is reducedto the barest minimum- This, however, introduces difllculties into. themelt coating operation, as the presence of suilicient plasticizer toinsure a .good melt is necessary for the efficient and speedy coating ofpape r With ,the use of restricted amounts of 'plasticizer the speed ofthe coating operation is restricted in that drying lines appear onpaperat certain speeds, if the melt is notlof the most desirable type. 'My

, process as adaptable to preventing the sticking of melt coatedpaperseven though the amo'unt of pIasticizer employed in the melt coat n ID-Q7 ation has been as much as basedupqlithe Ordinarily paper is wmeltcoated with a 09m! position consisting of cellulose acetate butyratehaving a high butyryl content, such a a butyryl;

- content of 50% and asubstantial proportion of a plasticizer which issuii'iciently solventof the cel lulose ester to form a good meltibutwhich will not give, tackiness after the meltcoating has cooled. A goodexample of a composition useful,

for melt coatingis a mixture of acellulose acetate butyrate having abutyryl content or approximately 47%, and 33 /3%, 'basedon the weight ofthe cellulose ester, of a plasticizer consisting ofthree parts ofdibutyl' sebacate and. two parts of butyl stearate. 'Thisfcomposition isheated to a temperature of 16 Ol70 Qandmay beapplied to paper in anydesired manner giving agood coating thereon. For instance, the meltcoating may ester which is employed in the melt com-r7 be p l d by'abead application in'which thepaper after coatingis run over a bladetor-smoothing purposes while still in a plastiocondition.

The paper which is been first baryta coated or the meltcoating may havebeen applied first, followed by the application of a baryta coatingthereto. i

The alcohol treatment'may be imparted to the melt coated, waterresistant {paper either before, during, or after the application of aphotosensitive emulsion thereto. For instance, after a paperhas beenmelt coatedtheipaper may be passed through a heated chamber, 511611338heated to 190 F., in which chamber the alcohol is flowed out onto' thepaper'and-almost immediately evaporated therefrom. In order toincrease'the speed s of removal of the alcohol from the paper thus coated, boththecoating operation and theevapcrating operation may take place withinthe heated chamber for: the sake of convenience After the paper'has beentreated with alcohol in accordance with my process photographic emulsionmay-be applied-thereto, preferably on thus coated may either have in thechamber within-which :the treatmentitooh the side of the paper to whichthe alcohol has not been applied (providing only one side of the,

If thephotographic emu-l simultaneously with the alcohol-treatment, itis ready after evaporation of the alcohol therefrom for use forphotographic purposes. After the paper has beenexposed, it may then bedeveloped,

fixed, and washed in the conventional manner whereupon it maybe passedover a hot metal sur-= face such as a metal drum having a temperature of200 260 F., the side of they paper which had been treatedwith thealcohol being contacted with the hot metal. The paper which had beentreated in accordance with my invention readily dries and fallsawayi'rom the hot metal surface withwhich it contacts.

Although the invention has been described using ethyl alcohol as thewetting liquid, it is to be tor roll 3 the side alcohol from the hopper.

ndersto d tha oth r .icwer alicbatir at alt may be employed or h smonohyd q .a inhaticwal atoms being especially:

of'r m a q thaalaahol; s r i a i d rable to %,..2192 methy-l or 1 hiizrth ai ment.

The ol n xampl il stratesmy invention;

fa whi ad'b enb ma coated earn r; ma d on bath-slate w th hat m -s i eI" v qellu o e a t te t ra er siib ltri se ac hutyl stearat'' as ve'scrib ed 121158410 Vivi ij e'antx'abrrtae be'ins. tra dEDYIth 'Q QW Uat tea-ap li ation, T

Pan 1 ispa sedb t een press re1l 1jaad pp1 a P ncamrrouhei stha who s eapp icatorralldin imoa oar o ethyl alcohol contained-iii the essere P r4 a d in turn ma d ns-t "surfa es;L melt coating whichit contacts. I

ik encl se chamb n ni' htthe am itatcr is found and throughwhich thepaperf. as aintained at a tem e atur o 0480 y th p aseor' a org-warm 3-ere r ue nearer centa n ee hol was jacketedand cool wat through thejacket to, minimize. e,

t t Q sand e qf'paner-fi- /z w r pu t ush the i anpliaat r whi pr x maty 400 mundae a wha h mel -coated s face Aim moistan z. athe a i a or thea e w s alm tim edi te r freed of alcohol duer to the: warm"aircirculatinit place. .i v The pape h n; coa e .9 2 theh mte m y n yril t the a1 hol-treatedg sided r ithout' stickine o themeta suriace.

Insteada lyin th anchor-bathe bead method, it be. applied by any, methodaby which the surface of the melt spraying the alcohol on toarapidlymovinkflria Per S ee i h a be -melt coated: hes

plicati n or alcoh maybe se ra ed tram he d yi g. or evaporatin -means{tbe-paaer-in-thw caseartemhe ap lication-ot-tne-caloohd tbeinej ed intoev mte ins-cQn tima.

' es i ates he-ha l n an ethe v po a ion bt 1 I cient to dampencrmoistenthatsurfacer Great er quantities will tend to run oil ot'the paper andwould be uneconomical-in the excessive insect.

rne-acehqis p e erred or-g ar hdae- Q fairlyhigh conc ntration h as e lh alo hol; However, more dilute alcohol mayhe -eonv ployed withinthe'scone -oi'cur intention; The water, howeyer idilutes t eialcohoivandsthus a larger quantity'of liquid, thaniri-thosacases l where amore.concentrated-alcoholisused. Asa general rule thealcoholemployedxshouldf'be': ota: V

at least concentration.

The ,amount of alcohol; which is-appliedlto thesurface of themelt-coatinsf fheedom be'f'sufllf alcohol. I have found that-theapplicatioa ot- 2-4 pounds of alcoholyper IOOQ'squar feet of of thepaper contaqtingfltherqll. 1e papendried coatingilis" mois'e tened withthe alcohol; suchx-as'by "flowing, or" h time is not of importance thedrying or removal of the alcohol may be accomplished as desired, such asby exposing the treated paper to the air for the desired time. Anydrying operation compatible with the conditions here may be employed forthe evaporation of the alcohol from the surface moistened therewith.

I claim:

1. A method of treating the surface of paper. containing a melt coatingof a cellulose ester and a plasticizer to inhibit tackiness whencontacted with a hot surface which comprises contacting at least onesurface of paper melt coated with a mixture of a cellulose ester and aplasticizer with only sufficient alcohol of 1-4 carbon atoms to wet thesame; and evaporating the alcohol from that surface.

2. A method of treating at least one surface of paper containing a meltcoating of a cellulose ester and a plasticizer which comprisescontacting at least one surface of paper melt-coated with a mixture of acellulose ester and a plasticizer with only sufficient'e'thyl alcohol towet the same. and evaporating the alcohol from that surface.

3. A method of preventing melt coated paper from sticking to hot dryingsurfaces which comprises treating the surface of the paper containing amelt coating of cellulose acetate butyrate and a plasticizer thereonwith only sufficient lower monohydroxy aliphatic alcohol of 1-4 carbonatoms to wet the same and evaporating the alcohol from the surface ofthe coating.

4. A method of preventing melt coated paper from sticking to hot dryingsurfaces which comprises treating the surface of the paper containing amelt coating of cellulose acetate butyrate and a plasticiz er thereonwith only sufficient ethyl alcohol to wet the same and evaporating thealcohol from that surface.

5. A method of treating melt-coated paper,

which has been baryta coated and then meltcoated with a mixture ofcellulose butyrate and a plasticizer which comprises treating thesurface which has not been baryta coated with only sufficient ethylalcohol to wet the same and evaporating the alcohol from that surface.

a'mixture of a cellulose ester and'a plasticizer with only sufficientmethyl alcohol to wet the same. and then evaporating the alcohol fromthat surface.

WENDELL H. MCDOWELL.

